Commercial propulsion battery chargers, especially for off-road vehicles such as golf cars (either mounted on-board or off-board the vehicle), are usually designed as stand-alone units and are often manufactured by a different company than the supplier of the propulsion drive system. Battery voltage, charge current, and sometimes the slope of the charge current and/or the slope of the battery voltage versus time near the end of charge are used in the control of these commercial battery chargers. Today's commercial chargers with their unsophisticated control tend to overcharge the batteries, or improperly charge either aged batteries or batteries that are at temperatures significantly different than 80.degree. F. Overcharging wastes energy, increases the required battery watering maintenance, and significantly reduces battery life. Maintenance personnel errors, including failure to start the charger or premature termination of the charge function, are often not detected. If the battery is not properly charged, then during the next use cycle, excessive discharge may occur and result in reduced battery life and poor vehicle performance.